Recuperator for gas turbine powerplants



Aug. 23, 1966 c. HEM$woRTH ET AL 3,267,673

RECUPERATOR FOR GAS TURBINE POWERPLANTS I5 Sheets-Sheet 1 Original FiledJuly 13, 1964 o u 0 noun 0 O D INVENTORJ. 44487016. x/iwwaerx/ 22-2 AJT/EWdf Aug. 23, 1966 HEMSWQRTH ET AL 3,267,673

RECUPERATOR FOR GAS TURBINE POWERPLANTS Original Filed July 13, 1964 3Sheets-Sheet 2 N w A ri A ar/eawar Q .J? F

Aug. 23, 1966 M. c. HEMSWORTH ET AL 3,267,673

RECUPERATOR FOR GAS TURBINE POWERPLANTS I5 Sheets-Sheet 5 OriginalFiled. July 15, 1964 Quinn l ll INVENTOR-fi 3,267,673 RECUPERATOR FORGAS TURBINE POWERPLANTS Martin Carl Hernsworth, Cincinnati, Ohio, andTed Floyd Stirgwolt, Manchester, Mass, assignors to General ElectricCompany, a corporation of New York Continuation of application Ser. No.382,046, July 13,

1964. This application Oct. 22, 1965, Ser. No. 513,610 12 Claims. (Cl.60-6951) This application is a continuation of applicants copendingapplication entitled, Recuperative.Arrangement for Gas TurbinePowerplants, Serial No. 382,046, filed July 13, 1964, and assigned tothe assignee of this invention.

This invention relates to a recuperative arrangement for gas turbineengines and, more particularly, to a structural arrangement for arecuperator which is relatively lightweight and substantially free ofthermal stresses.

Gas turbine powerplants have been provided with recuperators in the pastin order to recover thermal energy and thereby reduce fuel consumption.A recuperator is a heat exchanger through which exhaust fluid from theturbine is directed prior to being discharged from the powerplant, theexhaust fluid being passed in heat exchange relationship with compressordischarge fluid which is directed through the recuperator prior to beingsupplied to the powerplant combustor. As a result of the heat exchangeprocess, the compressed fluid is heated and supplied to the combustor ata higher temperature and the exhaust fluid is cooled. The net effect ofthe process is to increase the overall thermal efficiency of thepowerplant since less fuel is required to produce a given turbine inlettemperature.

The elements of a recuperator are subjected to wide temperaturevariations. When the powerplant is not operating, the various elementsare at a relatively low uniform ambient temperature. During powerplantoperation, different elements are subjected to different temperatures,and some elements are even exposed to fluids at widely varyingtemperatures, the natural tendency of the elements being to expand andcontract in response to temperature changes. The usual practice,however, has been to interconnect the various elements such that asubstantially rigid structure is formed. Consequently, individualelements normally have little freedom to expand and contract in responseto temperature changes, and rigidly interconnected elements may eventend to expand and contract in opposition to each other. With normalthermal expansion and contraction thus restrained, the elements of therecuperator are subjected to undesirable thermal stresses. In time,these stresses may cause damage to, or even failure of, the recuperator.For example, repeated stresses may eventually cause fatigue and crackingof the various elements. As a result of even minor cracking, leakage ofthe compressed fluid into the exhaust fluid in the recuperator can be aproblem in view of the substantial pressure difference between the twofluids. When such leakage occurs, there is a loss to the system of theenergy consumed in compressing that portion of the compressor dischargefluid which is lost. It will thus be obvious that a significant amountof leakage can eliminate the increased thermal efficiency whichotherwise would be obtained by use of the recuperator as well as causingpower loss.

It is an object of this invention to provide for gas turbine powerplantsan improved highly efiicient recuperator which is substantially free ofthermal stresses.

Another object of this invention is to provide an improved recuperativearrangement which is both relatively lightweight and substantially freeof thermal stresses.

It is a further object of this invention to provide a nited StatesPatent "ice recuperative arrangement which has low leakage withouthaving substantial thermal stresses.

A still further object of this invention is to provide a recuperativearrangement which is simple in design and relatively easy andinexpensive to manufacture.

Briefly stated, in accordance with the illustrated embodiments of thisinvention, a gas turbine powerplant is provided with a heat exchanger,or recuperator, in the passageway connecting the turbine to thepowerplant discharge opening. In the recuperator, the exhaust fluid fromthe turbine is passed in heat exchange relationship with compressedfluid ducted from the discharge portion of the powerplant compressor.From the recuperator, the heated compressed fluid is directed to theinlet portion of the powerplant combustor. First and second toroidalheaders surround the engine upstream of the discharge opening, theheaders being positioned in radially spaced relationship. First ductingmeans is connected to the first header and second ducting means isconnected to the second header, one of the ducting means communicatingat its other end with the discharge portion of the compressor and theother of the ducting means communicating with the inlet portion of thecombustor. The first header is supported in position by the firstducting means, which is a rigid supporting means. Axially extendingsupport means connect the first ducting means and the first header tothe second header such that the second header is supported axiallytherefrom the second header providing no support function. The supportmeans permits substantially unrestrained relative radial movementbetween the first and second headers. A plurality of U-shaped heatexchange tubes join the headers in fluid flow relation and extenddownstream into the passageway between the turbine and the powerplantdischarge opening.

While the invention is distinctly claimed and particularly pointed outin the claims appended hereto, the invention, both as to organizationand content, will be better understood and appreciated, along with otherobjects and features thereof, from the following detailed descriptionwhen taken in conjunction with the drawing, in which:

FIG. 1 is a pictorial view, partially cut away, of a gas turbinepowerplant having a recuperator incorporating this invention;

FIG. 2 is a partial cross-sectional view of the recuperative gas turbineengine illustrated by FIG. 1;

FIG. 3 is a view taken along line 3-3 of FIG. 2 showing one of theradial partitions known as tube support sheets supporting the heatexchange tubes;

FIG. 4 is a fragmentary cross-sectional view of a gas turbine powerplanthaving a bypass arrangement for selectively directing a portion of thecombustion products directly to the discharge opening from thepowerplant turbine;

FIG. 5 is a fragmentary cross-sectional view of a gas turbine engineillustrating a second embodiment of support means for supporting thesecond header relative to the first header; and

FIG. 6 is a View illustrating a third embodiment of support means.

FIG. 7 is a top plan view of the structure shown by FIG. 6.

A gas turbine powerplant having a recupera-tor 10 incorporating oneembodiment of this invention is illustrated by FIGS. 1 and 2. Theparticular powerplant illustrated includes a gas generator 11 comprisinga multiple stage axial flow compressor 12, a combustor 13, and a gasgenerator turbine 14, arranged in axially spaced relation, the rotor ofthe turbine 14 driving the rotor of the compressor 12 through a hollowaxial shaft 15. A power turbine 16 is located axially downstream of thegas generator turbine 14 and drives a load through a shaft 17 eems s e3coaxially mounted for rotation within the shaft :15. The shaft 17 may,for example, drive a propeller to produce thrust for aircraftpropulsion. A discharge opening or exhaust nozzle 22 is spaced axiallydownstream of the power turbine 15, the discharge opening 22 beingconnected to the gas generator by a passageway indicated generally by23, the outer surface of the passageway 23 being defined by an outerexhaust casing 24 and the inner by a diverging conical Wall 240. As thisdescription proceeds, it will become obvious that the gas turbinestructure just described is illustrated only and that the invention isequally applicable to other arrangements. For example, the presentinvention can be utilized with engines of the turboprop type as well asthe turboshaft type just described.

Returning now to the illustrated embodiment, the combustion productsdischarged from the gas generator turbine 14 into the passageway 23 flowthrough the power turbine 16 and then are directed by means of axiallyspaced partitions 36 over the outer surfaces of a large number ofaxially extending U-shaped heat exchange tubes 31, the flow path of theexhaust fluid through the passageway 23 being shown by arrows in FIGS. 1and 2. As illustrated by FIG. 3, the radial partitions have openings 32therein through which the U-shaped tubes 31 are slidably supported. Inthis manner, the tubes 31 are supported radially while beingsubstantially unrestrained against axial movement. The partitions 34 arecomprised of relatively thin flexible material which is capable offlexing to accommodate expansion and contraction due to radialtemperature gradients. It will thus be seen that the tubes 31 aresupported in properly spaced relationship without being restrainedagainst either axial or radial expansion and contraction. As a result,the tubes 31 are substantially free of thermal stresses duringpowerplant operation. These tubes 31 will be discussed in greater detailat a later point in this description.

Referring again to FIGS. 1 and 2, one embodiment of the presentinvention will be described in detail. In the structural arrangementillustrated by FIGS. 1 and 2, an outer toroidal header 35 completelysurrounds the powerplant upstream of the discharge opening 22 and thepassageway 23. An inner toroidal header 35 similarly surrounds thepowcrplant, the outer and inner headers 35 and 36, respectively, beingaxially and radially spaced. As illustrated, the outer diameter of theinner header 3% and the inner diameter of the outer header 35 aresubstantially in radial alignment, and the inner header 35 is offsetaxially upstream of the outer header 35. A toroidal extraction frame 37is located upstream of the headers 35 and 36, the extraction frame 37surrouding the powerplant radially outward of the combustor 13. Theextraction frame 37, a relatively rigid support member, is divided by acircumferential partition into two annular sections 39 and at Theupstream annular section 39 is connected to the high pressure end of thecompressor 12 by a circumferential, diffusing duct 45, and thedownstream annular section it? is connected to the cornbustor 13 by aduct 46.

A first plurality of tubular ducts 47 connect the downstream annularsection 49 of the extraction frame 37 to the inn r header 3b. Thecylindrical ducts 47, which are spaced circumferentially about thepowerplant periphery, are rigid and thus support the inner header 36from the extraction frame 37. A second plurality of tubular ducts 48extend through the downstream annular section it and connect theupstream annular section 39 of the extraction frame 37 to the outerheader 35. The ducts 48 are similarly spaced equally about thepowerplant periphery and are interposed between adjacent ones of theducts 47. The ducts 4% do not support the outer header 35; a flexiblebellows 4? is provided in each duct 48 to permit free movement of theheader 35 relative to the extraction frame 37. Before proceeding with aa description of the support arrangement for the outer header 35, it isobserved that various members of ducts 4'7 and er; may be used; inpractice, six of each spaced at 60 intervals have been found to besatisfactory.

The outer header 35 is supported from the inner header 36 by athin-walled cylindrical member 59 secured to both the outer diameter ofthe inner header 3-6 and the inner diameter of the outer header 35. Thepiston forces exerted on the outer header 36 'by the compressed fluidare transmitted from the outer header 35 to the inner header 3% and thesupport ducts 47 through the member :31, in this manner, it will be seenthat the outer header 35 is axially supported from the inner, upstreamheader 3% ducts 47 having sumcien-t tensile strength to carry the pistonforces. These piston forces which must be carried by the member 50 andthe support ducts 4'7 may amount to many thousands of pounds of force.In addition to carrying the piston forces, the member 50 maintains thestatic radial positioning of the inner and outer headers while. becauseof its inherent flexibility, permitting substantially unrestrainedrelative expansion and contraction of the inner and outer headers. Forconvenience, it ray be said that the member or cylinder 5t permitsradial expansion and contraction of the outer, downstream header 35, butit will be obvious that the cylinder 59 actually accommodates relativeradial movement of both the inner and outer headers. In addition tosupporting the outer header 35 axially and positioning it radially, thethin-walled cylinder Silserves as a seal between the headers to preventescape of the combustion products flowing through the passageway 23 tothe atmosphere. To serve effectively asa seal, the cylinder 50 must becontinuously secured to the headers, preferably by brazing or welding. Aflexible cylinder 51 joins the outer periphery of the outer header 3 toexhaust casing 24, the cylinder 5?. permitting the header 35 to freelyexpand the contract relative to the exhaust casing 24 while acting as aseal to prevent leakage of the products of combustion.

As discussed above, it is essential that a gas turbine powerplant usedfor aircraft propulsion be lightweight as well as being substantiallyfree of thermal stresses. In order to achieve a lightweight design,experience dictates that the principal stresses in the structuralmembers, such as the headers and the extraction frame 37, be carried intension rather than in bending. Accordingly, the headers 35 and 36 andthe extraction frame 37 have circular crosssections to minimize bendingloads and therefore permit the use of lightweight, relativelythin-walled materials. To optimize the desired characteristics, it willbe obvious to those skilled in the art that the materials selected forthe various elements should have high strength and good fatiguecharacteristics so that the thermal stress relieving capability of thestructure described above is not exceeded.

The U-shaped heat exchange tubes 31 are the last elements assembled whenfabricating the recuperator 10. With the headers 35and 36 and the radialpartitions 3% in place, each tube 31 is inserted axially from thedownstream end of the recuperator 10 through the axially alignedopenings 32 in the partitions 30 and into axial openings 52 in theheaders. It is essential that the openings 52 be axial in order to makepossible this simplified insertion and removal of the tubes 31. Thetubes are then brazed to the headers 35 and 36. With the tubes 31 thusrestrained at their upstream ends only, they are free to expand andcontract axially in response to temperature changes by sliding throughthe openings 32 in the radial partitions 3'9. As discussed previously,the partitions 30 are relatively flexible and thus are capable ofaccommodating radial thermal expansion and contraction of the heatexchange tubes 31 without subjecting the tubes 31 to substantial thermalstresses.

The operation of the recuperator it? will now be described. Compressedfluid from the high pressure end of the compressor 12 flows through thecircumferential duct 45 into the upstream annular section 39 of theextraction frame 37, from which it is delivered through the firstplurality of ducts 47 to the outer, downstream header 35. From thetoroidal header 35, the compressed fluid enters the U-shaped heatexchange tubes 31 where it is heated by combustion products in thepassageway 23 contacting the outer surfaces of the tubes 31. The heatedfluid then enters the upstream, inner header 36, from which it isdirected through the ducts 48 to the extraction frame 37 and thence tothe combustor 13. It may be said that the ducts 47 and the outer header35 serve as a manifold arrangement for supplying the compressed air fromthe extraction frame 37 to the tubes 31 and that the inner header 36 andthe ducts 48 serve as a manifold arrangement for delivering thecompressed air from the tubes 31 to the extraction frame. Followingcombustion, the high temperature, high pressure products of combustiondrive the gas generator turbine 14 and the power turbine 16 prior tobeing directed by the radial partitions 39 across the outer surfaces ofthe heat exchange tubes 31 in cross flow heat exchange relationship. Thecooled combustion products are then discharged to the atmosphere throughthe discharge opening 22.

The total weight of a recuperator is also affected by its overall size.It will be noted that the recuperative arrangement illustrated by FIGS.1-3 directs all of the exhaust fluid through the recuperator under alloperating conditions. It is therefore a requirement that the recuperatorbe large enough to handle the maximum flow rates which occur when thepowerplant is operating under full load conditions. This type ofpowerplant is thus most efiicient when operating at full power. Duringpart power operation, both the capacity and weight are greater thanrequired. As a result, the powerplant efficiency is reduced at partpower. It is Well known, however, that some gas turbine engines arenormally run at part power settings. It is therefore sometimes desirableto design the recuperator to provide most eflicient operation at partpower. A recuperative powerplant utilizing this invention for efficientpart power operation is illustrated by FIG. 4.

The powerplant of FIG. 4 is substantially similar to the one illustratedby FIGS. 13, similar elements being denoted =by the same numerals. Thefluid handling elements comprising the recuperator are, however, sizedto accommodate only a portion of the full load gas flow. The elementsare substantially lighter than the counterpart elements of thepowerplant shown by FIGS. 1-3. During part power operation, the entireflow of combustion products passes through a first passageway 60 andcontacts the outer surfaces of the heat exchange tubes 31 before beingdischarged through the opening 22. When the flow of exhaust fluids isgreater than can be accommodated through the first exhaust passageway60, valve plates 61, one of which is illustrated, are moved from theclosed positions shown by solid lines in FIG. 4 to the open positionsillustrated by broken lines by means of a suitable operating mechanismsuch as the hydraulic cylinder and piston 62 illustrated. With the valveplates 61 in the open positions, the excess flow at high power settingscan be bypassed through a second passageway 63 and discharged through anozzle 64. This arrangement is thus most efficient at normal part poweroperation.

Referring now to FIG. 5, a second embodiment of the present inventionwill be described. As with FIG. 4, unchanged elements are identified inFIG. 5 with the same numerals as in FIGS. 1-3. This second structuralarrangement has an outer toroidal header 70 completely surrounding thepowerplant upstream of the discharge opening 22 and the passageway 23.An inner toroidal header 71 similarly surrounds the powerplant, theheaders 70 and 71 being in axial alignment and radially spacedrelationship. As in the first embodiment, a toroidal extraction frame 37is located upstream of the headers 70 and 71, and the inner header 71 issupported therefrom by a first plurality of tubular ducts 47. A secondplurality of tubular ducts 4S flexibly connect the extraction frame 37and the outer header 7 0, the outer header being supported from theinner header 71 and the extraction frame 37 by an annular support member72, which is secured to both headers and has a V-shaped cross-section.The support member 72 is comprised of inner and outer conical-shapedflexible portions 73 and 74, respectively. The inner portion 73 issecured to the outer diameter of the inner header 71 by brazing orwelding and diverges radially outward therefrom in the axiallydownstream direction. The outer portion 74 is similarly secured to theouter header 70, the outer portion 74 converging radially inwardtherefrom in the axially downstream direction. The flexible portions 73and 74 are joined at their downstream ends to form the V-shaped supportmember 72. The axial length of the support member 72 is substantiallygreater than the radial spacing between the headers, the large pistonforces developed on the outer header 70 by the compressed fluid therebybeing transmitted through the members 73 and 74 primarily in tension andcompression rather than in bending. In this manner, the outer header 70is axially supported by the inner header 71 in axial alignment with theinner header. In addition, the support member 72 maintains the staticradial positioning of the outer and inner headers while, because of theinherent flexibility of the conical-shaped members 73 and 74, permittingsubstantially unrestrained relative thermal expansion and contraction ofthe headers. The support member 72 also acts as a seal between theheaders.

A third embodiment of the invention is illustrated by FIGS. 6 and 7. Inthis thhd structural arrangement, an outer toroidal header and an innertoroidal header 8 1 circumferentially surround the powerplant, theheaders being axially aligned and in radially spaced relationship. Theinner header 81 is supported from an extraction frame (not shown) by afirst plurality of rigid tubular ducts 82. As illustrated, a portion 82'of each of the ducts 82 is in axial alignment with the outer header 80.A second plurality of tubular ducts 83 flexibly connect the extractionframe to the outer header 80. The outer header 80 is axially supportedfrom the portions 8-2 of the ducts 82 by axial tie rods 84 which arepivotally connected to both ducts 83 adjacent to the outer header 80 andto the duct portions 82'. The tie rods 84 thus transmit the pistonforces from the outer header 80 to the support ducts S2 in tension. Thepivotal connections of the axial tie rods 84 permit substantiallyunrestrained relative expansion and contraction of the headers. Aseparate sealing arrangement 85 seals the circumferential space betweenthe headers.

From the foregoing, it Will be appreciated that the recupenativearrangements of this invention provide relatively lightweight structureswhich are substantially free of thermal stresses. Therefore, thearrangements make possible the attainment of low leakage and highlyeflicient operation.

It will be understood that the invention is not limited to the specificdetails of construction and arrangement of the embodiments illustratedand described herein since changes and modifications will be obvious tothose skilled in the art. For example, other arrangements forinterconnecting the headers may be utilized. Radial abutting surfacesmay be used to transmit the piston forces without preventing relativeradial movement. Similarly, cylindrical, overlapping plates joined byslidab-le nadial pins can be used to interconnect the headers. It willalso occur to thoes skilled in the art that the extraction frame 37could be eliminated and that the ducts could directly connect theheaders to the discharge portion of the compressor 12 and the combustor13. Similarly, other embodiments as well as the first embodiment of theinvention may be used in conjunction with a bypass arrangement of thetype illustrated by FIG. 4. It is therefore intended to cover in theappended claims all such changes and modifications which may occur tothose skilled in the art without departing from the true spirit andscope of the invention.

What is claimed as new and desired to secure by Letters Patent of theUnited States is:

i. In a gas turbine powerplant having in axially spaced relationship afluid compressor, a combustor, a turbine dnivingly connected to saidcompressor, a discharge opening, and a passageway connecting saidturbine to said discharge opening, a recuperator comprising, incombination:

(a) first manifold means comprising a first toroidal header and firstducting means in fluid flow relationship,

(b) second manifold means comprising a second toroidal header and secondducting means in fluid flow relationship,

(c) one of said first and second ducting means communicating with thedischarge portion of the compressor and the other ducting meanscommunicating with the inlet portion of the combustor,

(d) said first ducting means secured to said first header such that saidfirst header is supported by said first ducting means, and said secondmanifold means including flexible means such that second header issubstantially unsupported by said second ducting means,

(e) axially extending support means connecting said first manifold meansand said second header such that said second header is supported axiallyby said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond head-e (f) and a plurality of heat exchange elements connectingsaid first and second headers in fluid flow relation, said heat exchangeelements extending into the passageway between the turbine and thedischarge opening in heat exchange relation to combustion productsflowing therethrough,

(g) whereby fluid supplied to said heat exchange elements from thecompressor is heated by the cornbustion products prior to beingdelivered to the combustor.

2. In a gas turbine power plant having in axially spaced relationship afluid compressor, a combustor, a turbine drivingly connected to saidcompressor, a discharge opening, and a passageway connecting saidturbine to said discharge opening, a recuperator comprising, incombination:

(a) first manifold means comprising a first toroidal header positionedaxially upstream of the discharge opening and first ducting meansconnected to said first header.

( b) second manifold means comprising a second toroidal headerpositioned axially upstream of the discharge opening and second ductingmeans connected to said second header, said second header in radiallyspaced relationship to said first header,

(c) one of said first and second ducting means communicating with thedischarge portion of the cornpressor and the other ducting meanscommunicating with the inlet portion of the combustor,

((1) said first ducting means secured to said first header such thatsaid first header is supported by said first ducting means, and saidsecond manifold means in cluding flexible means such that said secondheader is substantially unsupported by said second ducting means,

(e) axially extending support means connecting said first manifold meansand said second header such that said second header is supported axiallyby said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond header,

(f) and a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangetubes being U-shaped and extending axially downstream from said headersinto the passageway between the turbine and the discharge opening inheat exchange relation to combus ion products flowing therethrough, (g)whereby fluid supplied to said heat exchange tubes from the compressoris heated by the combustion products prior to being delivered to thecombustor.

in a gas turbine powerpiant having axially spaced r ttionship a fluidcompressor, a combustor, a turbine drivi gi connected to saidcompressor, a discharge openbination:

(a) a first toroidal header having circular cross-section p sitionedaxially upstream of the discharge ope.- e

(b) a second toroidal header having circular crosssection positionedaxially upstream of the discharge opening and in re ially spacedrelationship to said first header,

(c) a first set of tubular ducts connected to said first header,

(d) a second set of tubular ducts connected to said second header,

(e) one of said sets of tubular ducts communicating with the dischargeportion of the compressor and the other set of ducts communicating withthe inlet portion of the combustor,

(i) said first set of ducts supporting said first header, and saidsecond set of ducts including flexible means such that said secondheader is substantially unsupsaid second set of ducts,

of axially extending tie rods connecting said first set of tubular ductsand said second set of tubular ducts adjacent said second header tosupport axially said second header downstream of said first set ofducts, (11) said axially extending tie rods pivotally connected to saidfirst set of ducts and said second set of ducts so as to permitsubstantially unrestrained radial expansion and contraction of saidsecond header, (i) and a plurality of heat exchange tubes fixed to anconnecting said first and second headers in fluid fl relation, said heatexchange tubes being U- shaped and extending axially downstream fromsaid headers into the passageway between the turbine and the dischargeopening in heat exchange relation to combustion products flowingtherethrough, (j) whereby fluid supplied to said heat exchange tu esfrom the compressor is heated by the combustion products prior to beingdelivered to the combustor. In a turbine powerplant having in axiallyspaced relationship a fluid compressor, a combustor, a turbine rivinglyconnected to said compressor, a discharge openand a passagewayconnecting said turbine to said scharge opening, a recuperatorcomprising, in combination:

(a) a first toroidal header having circular cross-section positionedaxially upstream of tr e discharge opening,

(b) a second toroidal he der having circular crosssection positionedaxially upstream of the discharge opening,

(c) said first and second headers in axial and radial spaced rationship,the rad al relationship being such that the inner diameter of the outerheader and the outer diameter of the inner header are substantially inradial alignment,

(d) a first set of tubular ducts connected to the upstream header,

(e) a second set of tubular ducts connected to the downstream header,

(i) one of said sets of tubular ducts communicating with tce dischargeportion of the compressor and the other set of ducts communicating withthe inlet portion of the cornbustor, said first set of ducts supportingthe upstream header, and said second set of ducts including flexiblemeans such that said downstream header is substantially unsupported bysaid second set of ducts,

(g) a relatively flexible thin-walled cylinder tangentially secured tothe outer header at its inner diameter and the inner header at its outerdiameter such that the downstream header is axially supported from theupstream header,

(h) said relatively flexible thin-walled cylinder permittingsubstantially unrestrained radial expansion and contraction of thedownstream header,

(i) and a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangetubes being U- shaped and extending axially downstream from said headersinto the passageway between the turbine and the discharge opening inheat exchange relation to combustion products flowing therethrough,

(j) whereby fluid supplied to said heat exchange elements from thecompressor is heated by the combustion products prior to being deliveredto the combustor.

5. In a gas turbine powerplant having in axially spaced relationship afluid compressor, a combustor, a turbine driv-ingly connected to saidcompressor, a discharge opening, and a passageway connecting saidturbine to said discharge opening, a recuperator comprising, incombination:

(a) a first toroidal header having circular cross-section positionedaxially upstream of the discharge opening,

(b) a second torodial header having circular crosssection axiallyaligned with and radially spaced from said first header,

() a first set of tubular ducts connected to said first header,

(d) a second set of tubular ducts second header,

(e) one of said sets of tubular ducts communicating with the dischargeportion of the compressor and the other set of ducts communicating withthe inlet portion of the cornbustor,

(f) said first set of ducts supporting said first header, and saidsecond set of ducts including flexible means such that second header issubstantially unsupported by said second set of ducts,

(g) an annular support member having V-shaped crosssection secured tosaid headers and axially supporting said second header from said firstheader,

(h) said annular support member comprising inner and Outer substantiallyconical-shaped flexible members secured to said inner and outer headers,respectively, and extending axially downstream therefrom said innermember diverging radially outward and said outer member convergingradially inward in the axially downstream direction, said inner andouter members being joined at their downstream ends,

(i) the axial length of said annular support member being greater thanthe radial spacing between said inner and outer headers,

(j) said flexible inner and outer members permitting substantiallyunrestrained radial expansion and contraction of said second header,

(k) and a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangeelements being U- shaped and extending axially downstream from saidheaders into the passageway between the turbine and the dischargeopening in heat exchange relation to combustion products flowingtherethrough,

(1) whereby fluid supplied to said heat exchange elements from thecompressor is heated by the combustion products prior to being deliveredto the combustor.

connected to said 6. In a gas turbine powerplant having in axiallyspaced relationship a fluid compressor, a cornbustor, a turbinedrivingly connected to said compressor, a discharge opening, and apassageway connecting said turbine to said discharge opening, arecuperator comprising, in combination:

(a) first manifold means comprising a first toroidal header positionedaxially upstream of the discharge opening and first ducting meansconnected to said first header,

(b) second manifold means comprising a second toroidal header positionedaxially upstream of the discharge opening, and second ducting meansincluding an expansible bellows,

(c) one of said first and second ducting means communicating with thedischarge portion of the compressor and the other ducting meanscommunicating with the inlet portion of the cornbustor,

(d) said first ducting means secured to said first header such that saidfirst header is supported by said first ducting means,

(e) axially extending support means connecting said first manifold meansand said second header such that said second header is supported axiallyby said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond header,

(f) and a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangetubes being U-shaped and extending axially downstream from said headersinto the passageway between the turbine and the discharge opening inheat exchange relation to combustion products flowing therethrough,

(g) whereby fluid supplied to said heat exchange tubes from thecompressor is heated by the combustion products prior to being deliveredto the combustor.

7. In a gas turbine powerplant having in axially spaced relationship afluid compressor, a cornbustor, a turbine drivingly connected to saidcompressor, a discharge opening, and a passageway connecting saidturbine to said discharge opening, a recuperator comprising, incombination:

(a) first manifold means comprising a first toroidal header positionedaxially upstream of the discharge opening and first ducting meansconnected to said first header,

(b) second manifold means comprising a second toroidal header positionedaxially upstream of the discharge opening and second ducting meansincluding an expansible bellows,

(c) one of said first and second ducting means communicating with thedischarge portion of the compressor and the other ducting meanscommunicating with the inlet portion of the cornbustor,

(d) said first ducting means secured to said first header such that saidfirst header is supported by said first ducting means,

(e) axially extending support means connecting said first manifold meansand said second header such that said second header is supported axiallyby said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond header,

(f) and a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers influid flow relation, said heat exchange tubesbeing U-shaped and extending axially downstream from said headers intothe passageway between the turbine and the discharge opening in heatexchange relation to combustion products flowing therethrough,

g) and supplemental support means in said passageway between the turbineand the discharge opening radially supporting said heat exchange tubesand permitting substantiaily unrestrained axial expansion andcontraction of said heat exchange tubes,

(h) whereby fluid supplied to said heat exchange tubes from thecompressor is heated by thencombustion products prior to being deliveredto the combustor.

8. A recuperative gas turbine powerplant comprising,

in combination: a

(a) a gas generator having in axially spaced relationship,a compressor,a combustor, and a turbine drivingly connected to said compressor,

(b) a discharge opening,

(c) first and second passageways connecting said turbine to saiddischarge opening, a (d) a valve for selectively permitting orpreventing fiow of combustion products through said second passageway,

(e) first manifold means comprising a first toroidal header positionedaxially upstream of said discharge opening and first ducting meansconnected to said first header,

(f) second manifold means comprising a second toroidal header positionedaxially upstream of said discharge opening and second ducting meansconnected to said second header, said second header in radially spacedrelationship to said first header,

(g) one of said'first and second ducting means communicating with thedischarge portion of said compressor and the other ducting meanscommunicating with the inlet portion of said cornbustor,

(h) said first ducting means secured to said first header such that saidfirst header is supported by said first ducting means; and said secondmanifold means including flexible means such that said second header issubstantially unsupported by said second ducting means,

(i) axially extending support means connecting said first manifold meansand said second header such that said second header is supported axiallyby said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond header,

(3') and a pluraiity of heat exchange tubes fixed to 7 and connectingsaid first and second headers in fiuid fiow relation, said heat exchangeelements being Ushaped and extending axiailydownstream from said headersinto said first passageway between the turbine and the discharge openingin heat exchange relation to combustion products fiowing therethrough,is

(k) whereby fiuid supplied to said 'heat exchange elements from thecompressor is heated by the combustion products flowing through saidfirst passageway prior to being delivered to the combustor.

9. A recu-perative gas turbine powerplant comprising,

in combination:

(a) a gas generator having in axially spaced relationship a compressor,a combustor, and a turbine drivingly connected to said compressor,

(b) a discharge opening, a

(c) first and second passageways connecting said turbine to saiddischarge opening,

(d) a valve for selectively permitting or preventing flow of combustionproducts through said second passageway,

(e) first manifold means comprising a first toroidal header positionedaxially upstream of the discharge opening and first ducting meansconnected to said first header,

(f) second manifold means comprising a second toroidal header positionedaxially upstream of the discharge opening and second ducting meansincluding an expansible beliows,

(g) one of said first and second ducting means communicating with thedischarge portion of the com- 12 pressor and the other ducting meanscommunicating with the inlet portion of the cornbus'tor,

(h) said first ducting means secured to said first header such that saidfirst header is supported by said first ducting means,

(i) axially extending support means connecting said tfirst manifoldmeans and said second header such that said second header is supportedaxially by said first manifold means, said support means permittingsubstantially unrestrained radial expansion and contraction of saidsecond header,

(3') a plurality of heat exchange tubes fixed to and connectingsaidwfirst and second headers in rfiuid fiow relation, said heatexchange elements being U-sha-ped and extending axially downstream tfromsaid headers into said first passageway between the turbine and thedischarge opening in heat exchange relation to combustion productsflowing there-through,

(k) supplemental support means in'said first passageway lbe tween theturbine and the discharge opening radially supporting said heat exchangetubes and permitting substantially unrestrained axial expansion andcontraction of said heat exchange tubes,

(1) whereby fiuid supplied to said heat exchange elements from thecompressor is heated by the COIHb'llS", tion products flowing throughsaid first passageway prior to being delivered to the combustor.

iii. A recuperative gas turbine powerplant comprising,

in combination:

(a) a gas generator having in axially spaced relationship a compressor,a combustor, and a turbine drivingly connected to said compressor,

(b) a discharge opening,

(c) first and second passageways connecting said turbine to saiddischarge opening, 7

(d) a valve for selectively permitting or preventing flow of combustionproducts through said second passageway,

(e) a first toroidal header having circular cross-section positionedaxially upstream oi? the discharge opening,

(f) a second toroidal header having circular cross-section positionedaxially upstream of the discharge opening and in Tadially spacedrelationship to said first header,

(g) a first set of tubular ducts connected to said first header,

(h) a second set of tubular ducts each including an expansible bellows,

(i) said second set of tubular ducts communicating with the dischargeportion of said compressor and said first set of tubular ductscommunicating with the inlet portion of said combustor,

(j) said first set of ducts supporting said first header,

(k) a plurality of axially extending tie rods connecting said first setof tubular ducts and said second set of tubular ducts adjacent saidsecond header to support axially said second header downstream of saidfirst set of ducts,

(1) said axially extending tie rods pivotally connected to said firstset of ducts and said second set of ducts so as to permit substantiallyunrestrained radial expansion and contraction of said second header,

(m) a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangeelements being U-shaped and extending axially downstream from saidheaders into said first passageway between the turbine and the dischargeopening in heat exchange relation to combustion products flowingtherethrough,

(n) and at least one relatively thin flexible partition radiallytraversing said first passageway, said partitron having a plurality ofopenings therein slidably receiving said heat exchange tubes so as toradially support said tubes and permit substantially unrestnained axialexpansion and contraction of said tubes,

() whereby fluid supplied to said heat exchange elements from thecompressor is heated by the combustion products flowing through saidfirst passageway prior to being delivered to the combustor.

11. A recuperative gas turbine powerplant comprising,

in combination:

(a) a gas generator having in axially spaced relationship a compressor,a combustor, and a turbine drivingly connected to said compressor,

(b) a discharge opening,

(c) first and second passageways connecting said turbine to saiddischarge opening,

(d) a valve for selectively permitting or preventing flow ot combustionproducts through said second passageway,

(e) a first toroidal header having circular cross-section positionedaxially upstream of the discharge opening,

(if) a second toroidal header having circular cross-section positionedaxially upstream of the discharge opening,

(g) said first and second headers in axial and radial spacedrelationship, the radial relationship being such that the inner diameterof the outer header and the outer diameter at the inner header aresubstantially in radial alignment.

(h) a first set of tubular ducts connected to the upstream header,

(i) a second set of tubular ducts each including an expansible bellows,

(j) said second set of tubular ducts communicating with the dischargeportion of said compressor and said first set of tubular ductscommunicating with the inlet portion of said combustor,

(k) said first set oi ducts supporting the upstream header,

(1) a relatively flexible thin-walled cylinder tangentially secured tothe outer header at its inner diameter and the inner header at its outerdiameter such that the downstream header is axially supported from theupstream header,

(m) said relatively flexible thin-walled cylinder permittingsubstantially unrestrained radial expansion and contraction of thedownstream header,

(n) a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangeelements being U-shaped and extending axially downstream from saidheaders into said first passageway between the turbine and the dischargeopening in heat exchange relation to combustion products flowingtherethrough,

(o) and at least one relatively thin flexible partition radiallytraversing said first passageway, said partition having a plurality ofopenings therein slidably receiving said heat exchange tubes so as toradially support said tubes and permit substantially unrestrained axialexpansion and contraction of said tubes,

(p) whereby fluid supplied to said heat exchange elements trom thecompressor is heated by the combustion products flowing through saidfirst passageway prior to being delivered to the combustor.

12. A recuperative gas turbine powerplant comprising,

in combination:

(a) a gas generator having in axially spaced relationship a compressor,a combustor, and a turbine driv- 6 ingly connected to said compressor,(b) a discharge opening,

(c) first and second passageways connecting said turlbine to saiddischarge opening,

(d) a valve for selectively permitting or preventing flow of combustionproducts through said second passageway,

(e) a first toroidal header having circular cross-section positionedaxially upstream of the discharge opening,

(if) a second toroidal header having circular cross-section axiallyaligned with and radially spaced lfrom said first header,

(g) a first set of tubular ducts connected to said first header,

(h) a second set of tubular ducts each including an expansible bellows,

(i) said second set of tubular ducts communicating with the dischargeportion of said compressors and said first set of tubular ductscommunicating with the inlet portion ot said combustor,

(j) said first set of ducts supporting said first header,

(k) an annular support member having a V-shaped cross-section secured tosaid headers and axially supporting said second header from said firstheader,

( l) said annular support member com-prising inner and outersubstantially conical-shaped flexible members secured to said inner andouter headers, respectively, and extending axially downstream therefromsaid inner member diverging radially outward and said outer memberconverging radially inward in the axially downstream direction, saidinner and outer members being joined at their downstream ends,

(m) the axial length of said annular support member being greater thanthe radial spacing between said inner and outer headers,

(n) said flexible inner and outer members permitting substantiallyunrestrained radial expansion and contraction of said second header,

(0) a plurality of heat exchange tubes fixed to and connecting saidfirst and second headers in fluid flow relation, said heat exchangeelements being U-shaped and extending axially downstream trom saidheaders into said first passageway between the turbine and the dischargeopening in heat exchange relation to combustion products flowingtherethrough,

(p) and at least one relatively thin flexible partition radiallytraversing said first passageway, said partition having a plurality ofopenings therein slidably receiving said heat exchange tubes so as toradially support said tubes and permit substantially unrestrained axialexpansion and contraction of said tubes,

(q) whereby fluid supplied to said heat exchange elements from thecompressor is heated by the combustion products flowing through saidfirst passageway prior to being delivered to the combustor.

MARK NEWMAN, Primary Examiner.

R. D. BLAKESLEE, Assistant Examiner.

1. IN A GAS TURBINE POWERPLANT HAVING IN AXIALLY SPACED RELATIONSHIP AFLUID COMPRESSOR, A COMBUSTOR, A TURBINE DRIVINGLY CONNECTED TO SAIDCOMPRESSOR, A DISCHARGE OPENING, AND A PASSAGEWAY CONNECTING SAIDTURBINE TO SAID DISCHARGE OPENING, A RECUPERATOR COMPRISING, INCOMBINATION: (A) FIRST MANIFOLD MEANS COMPRISING A FIRST TOROIDAL HEADERAND FIRST DUCTING MEANS IN FLUID FLOW RELATIONSHIP, (B) SECOND MANIFOLDMEANS COMPRISING A SECOND TOROIDAL HEADER AND SECOND DUCTING MEANS INFLUID FLOW RELATIONSHIP, (C) ONE OF SAID FIRST AND SECOND DUCTING MEANSCOMMUNICATING WITH THE DISCHARGE PORTION OF THE COMPRESSOR AND THE OTHERDUCTING MEANS COMMUNICATING WITH THE INLET PORTION OF THE COMBUSTOR, (D)SAID FIRST DUCTING MEANS SECURED TO SAID FIRST HEADER SUCH THAT SAIDFIRST HEADER IS SUPPORTED BY SAID FIRST DUCTING MEANS, AND SAID SECONDMANIFOLD MEANS INCLUDING FLEXIBLE MEANS SUCH THAT SECOND HEADER ISSUBSTANTIALLY UNSUPPORTED BY SAID SECOND DUCTING MEANS, (E) AXIALLYEXTENDING SUPPORT MEANS CONNECTING SAID FIRST MANIFOLD MEANS AND SAIDSECOND HEADER SUCH THAT SAID SECOND HEADER IS SUPPORTED AXIALLY BY SAIDFIRST MAINFOLD MEANS, SAID SUPPORT MEANS PERMITTING SUBSTANTIALLYUNRESTRAINED RADIAL EXPANSION AND CONTRACTION OF SAID SECOND HEADER, (F)AND A PLURALITY OF HEAT EXCHANGE ELEMENTS CONNECTING SAID FIRST ANDSECOND HEADERS IN FLUID FLOW RELATION, SAID HEAT EXCHANGE ELEMENTSEXTENDING INTO THE PASSAGEWAY BETWEEN THE TURBINE AND THE DISCHARGEOPENING IN HEAT EXCHANGE RELATION TO COMBUSTION PRODUCTS FLOWINGTHERETHROUGH, (G) WHEREBY FLUID SUPPLIED TO SAID HEAT EXCHANGE ELEMENTSFROM THE COMPRESSOR IS HEATED BY THE COMBUSTION PRODUCTS PRIOR TO BEINGDELIVERED TO THE COMBUSTOR.